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Single motor protection with VFD per Article 430.130

Question asked by tom.brenner on Oct 18, 2019
Latest reply on Oct 22, 2019 by

Looking for interpretation of Article 430.130(A)(1) and (2) with respect to Branch-Circuit Short-Circuit and Ground Fault Protective device rating for single motor applications when a VFD is installed. The article refers back to 430.52 which really addresses manual motor controller and overload relay configurations, limiting the maximum value to 400% of motor full load current (when protected by a non-time delay fuse or circuit breaker). However the VFD in this case provides overload, ground fault and short circuit protection for the motor; the branch circuit protective device protects the VFD.  In some cases, a larger protective device is required for the VFD.  If a higher BCP value has been UL Listed for use with the VFD per UL 61800-5-1 or UL 508C and is specified in the VFD manufacturer's instructions, can this override Article 430.52 and Table 430-52 since overload and short circuit protection is provided by the VFD?